It is well known to use mineral fibres, generally in consolidated form with binder, as fire protection products. Fire protection products are used in a wide variety of situations. In certain particular cases the risk is of a fire which would lead to an extremely fast rise in temperature. Such situations include off-shore applications such as on oil rigs where there is a risk of hydrocarbon fire and marine applications in ships due to the fact that they carry their own fuel, and so on. Other circumstances in which there is a risk of extremely rapid temperature rise include chemical plants where there is a risk of explosive fire and in tunnels. Further circumstances in which there is a risk of extremely rapid temperature rise and/or very little presence of oxygen includes fire doors, sandwich panels and roof boards.
WO 2005/035895 gives an example of a mineral fibre insulation product particularly for use in ship building. The content of oxides in the mineral fibre composition is: SiO2 25 to 55%, Al2O3 16 to 27%, CaO 6 to 20%, MgO 1 to 5%, FeO 15 to 15%, and alkali metal oxides R2O 10 to 14 7%.
Various types of stone wool are well known for use in fire protection applications but for applications such as those where very high and rapid temperature rise is expected (for instance where the temperature increase surpasses what is described in the standard fire curve and test method described in ISO 834-1 test procedure IMO Res 754 (18): Recommendation on fire resistance tests for “A”, “B” and “F” class divisions), currently available stone wool usually can meet the stringent requirements for use in these circumstances only if it is used at a very high density and/or high thickness. This can be disadvantageous as it adds to expense and to the weight of the product and its bulk. Ceramic products can also meet the stringent requirements of these circumstances but tend to be expensive to produce.
For instance, EP-A-1157974 is one example of many stone wool compositions for general insulation purposes. It does not discuss the specific requirements of products useful for fire protection in the unusual cases where it is necessary to protect against very high and rapid temperature rises.
Accordingly, it would be desirable to be able to provide a mineral fibre product capable of effectively providing fire protection in these stringent circumstances at lower densities and/or thicknesses. It would also be desirable to provide such a product which is technically and economically feasible to produce.